Perhaps the most widely used method for preserving vegetables and fruits is canning. Although the canned products have good storage characteristics, most canned vegetables and fruits undergo a certain amount of deterioration due primarily to the conventional heat processing used to sterilize the contents of the can. This deterioration generally involves softening of the vegetable or fruit material and a marked change in its texture and appearance as compared with the corresponding product in the fresh state. The differences between the fresh and canned products are readily perceived by the consumer and they play an important role in determining consumer preference for a particular product. Accordingly, considerable effort has been devoted over the years to the development of processing techniques which minimize the deterioration that normally accompanies the canning of vegetables and fruits.
Among the techniques investigated for reducing texture deterioration in canned vegetables and fruits are adjustment of pH, time/temperature adjustments of blanching steps used in the canning process, addition of calcium salts and the addition of chemical agents which inhibit microbial growth and permit the use of less severe heating conditions for the canned material. Combinations of these techniques have also been employed but the most widely used method for retaining texture in canned vegetables or fruits appears to be the addition of calcium salts such as calcium chloride, calcium lactate, calcium citrate, calcium malate and calcium phosphate. While treatment with calcium salts is effective to some extent in providing improved texture, such treatment may adversely affect the taste of the treated and canned product. Thus, prior art methods do not provide a totally satisfactory canned product.